I find Sudoku puzzles, particularly the hand-crafted rather than computer-generated ones, to be an addictive form of intellectual entertainment. The delight of seeing a solution unfold can be comparable to seeing a new vista with each step in a Japanese garden.

Logic is the key to solving Sudoku puzzles, and hence they can be a good class activity to combine simple language with higher-order thinking skills. Project or draw one on the board and encourage students to suggest where numbers can be placed.

For German-only classrooms, the words Zeile ("row"), Spalte ("column"), Block/Bereich ("3x3 block") will be useful, as well as oben/unten, links/rechts. Rules and tips in German, see Jankos Sudokuregeln. For hand-crafted puzzles, go to Sudoku Puzzles from the Guardian newspaper.